With this invention we intend to give the market a better, practical and cheaper formwork for the traditional pillar formworks used in iron and wood.
Formworks for pillars are known e.g. from DE29609259, using two segments of a plastic tube, which was sliced and divided lengthways along the tube axis before. The formwork is mounted by positioning both tube segments against each other thus forming the outer shell of the formwork in which an inner auxiliary formwork element can be inserted. Both tube segments are connected to each other by way of angled elements and bolts or the like. These angled elements have to be previously attached to both tube halves e.g. by gluing. As an alternative solution, a flat iron band is attached to one of the tube halves overlapping the gap between both tube segments. In addition, iron ribbons are secured around the formworks forcing the segments together.
In FR1322174 a conventional outer formwork is additionally provided with a thin layer serving as inner auxiliary formwork element in order to achieve a specific surface finish.
US5098059 describes a foam piece surrounded by a plastic layer. This plastic layer allows the foam piece to be easily removed from hardened concrete to be reused. However, in all cases no further details relating to the positioning, assembling and fixing of outer formworks for pillars of different shape are given.
Due to its texture in plastic the formwork according to the invention becomes light and the positioning is very easy and practical indeed.
More than that, this invention is very versatile because it permits the easy extension of the formwork because of the elements (5) from
where we can get rectangular or square sections when joined together to having always the same measure. That means that there is allways a standard element and the elements can be used in rectangular or square pillars. The elements are connected by male and female coupling means which are formed integrally by the ends of the standard elements and consist of male (4) and female (3) coupling means being removably connectable to each other. For the round sections the formwork must be made one for each diameter because the parts are fixed and can not be extended.
Until now, many traditional pillar formworks (in steel or wood) are in direct contact with the concrete and should be previously oiled and well cleaned later on when the job was finished. They are very heavy, they are difficult to position and transport and the price is very expensive. In this invention, the formworks, because they are very light and because the concrete is not adherent to plastic they are of very easy building and dismounting and anybody can do it even if it is not a technic worker. Due to the said before they don't need to be oiled or cleaned.
The formwork according to the invention is composed by two formworks (one exterior (5-4-3)- the real formwork and one interior (8) -a thin piece of plastic -which we are going to call a wrapper).
This interior wrapper is very important because it has the specific functions of isolating the exterior formwork from the contact with concrete and of giving the surface pillar the final polish appearance. This final surface permits direct painting.
This wrapper (8) is, of course, very cheap and is used only once. To prevent the dynamic forces of compression in the lateral walls the exterior formwork is provided with "ribs" (11) which give the formwork a better resistance and allow the fixing of vertical irons (7) which are directed to small mortar (10) previously embedded in the floor concrete. This also allows the formwork do not move while the concrete is dropped in.
The already above mentioned forces of compression, mostly in the large pillars, will be annulled by 3 or 4 metallic belts (12) disposed along the formwork and against the vertical irons (7) which provide the necessary resistance.
In the Fig 1 we can see a pillar formwork with ribs (11) and vertical iron (7) and the small mortar (10). Longitudinally we can see a metallic belt (12).
The Fig 2 represents a circular pillar formwork. To change the measures we need other elements (5) in different measures. This formwork is also formed by an interior wrapper (8).
The Fig 3 represents a pillar formwork for a square section. If we want to transform it for a rectangular section we only need to add elements (5) in two parallel walls.
In the Fig 4 we can see a small mortar (10) for the pillar bracing where the irons (7) come in and in the Fig 4-A we can see the small mortar (10) embedded in the floor concrete.
The Fig. 5 represents a perspective of a finished pillar with the wrapper (8).
Fig 6 intends to be a simple formwork for special cases when we need to make simultaneously the beam and the pillar. It's made by angled elements (13) which are closed by some vertical irons passing into rings to allow the horizontal dismount.